1. Field of the Invention
This invention relates to a rotary rectifier device for rotatable electrical machines having disc-type rectifier cells which are resiliently clamped by mounting means at the inner periphery of an annular or ring flange of a carrier-wheel.
2. Description of the Prior Art
A heretofore known rotatable rectifier device of this type is described in Swiss Pat. No. 499,201. In that device, several series-connected disc cells are each held between a rigid and a resilient heat sink plate and are bolted together in a column at the inner periphery of a carrier-wheel ring flange.
Such known disc cells have considerable advantages over conventional rectifiers having a housing with an area contact and a stranded-wire lead on the opposite side, because they have smaller dimensions and less weight. Due to the symmetrical shape of the disc cells, it is also not necessary to construct each rectifier type in two different embodiment for the different cirections of conduction. However, difficulties arise with the assembly of such disc cells, since the required contact pressure must be supplied from the outside, whereby the contact pressure must be distributed uniformly over the surfaces, and any possible deviation of the contact surfaces from plane-parallelism must be balanced or equalized by the clamping action. To make inspection measurements possible, he contact pressure must not fall below a predetermined minimum when the machine is standing still. On the other hand, during operation of the machine, the centrifugal force acting on the parts of the clamping system should reach a value no greater than a permissible value.
In the device of the aforementioned Swiss patent, however, these conditions are inadequately fulfilled. The resilient heat sink plates have only very short spring travel distance, so that considerable change can occur from the intended value of the contact pressure in the event of minor dimensional changes of parts of the clamping system, such as, for example, due to shrinking of insulation parts. For the same reason, there is no sufficiently uniform pressure distribution over the contact surfaces of the disc cell, particularly if the latter have minor deviations from plane-parallelism. The heat sinks and the spring elements are clamped in one operation, where the degree of tightening can have an additional uncontrollable influence on the magnitude of th contact pressure. A further disadvantage is that the individual parts can be assembled and adjusted only directly at the machine.